The present invention provides vapor phase corrosion inhibitor compositions and provides a method for inhibiting the corrosion of metal by contacting said metal with an active vapor phase corrosion inhibitor.
Various products made of metal, such as steel products, tend to oxidize during their production, storage or transportation. In order to prevent or minimize this problem, corrosion inhibitors of various types have been used for many years. Relatively recently, vapor phase inhibitors have been used to coat the metal. Hitherto, dicyclohexylamine nitrate (trademark: DICHAN, chemical formula (C.sub.6 H.sub.11).sub.2 NH.sub.2 NO.sub.2) and a salt of dicyclohexylamine with a fatty acid (trademark: FERROGUARD) have been commercialized and used as the inhibitor.
These known inhibitors are disadvantageous because gas derived from them, especially from DICHAN, can diffuse by a distance of only about 30 cm. at ambient temperatures. DICHAN has no solubility in oil, so that it cannot be used by adding it to a mineral oil, such as lubricating oil, light oil and the like. Similarly, FERROGUARD is an organic salt and therefore only slightly soluble in mineral oil. Because of such poor solubility in oil, these anticorrosive substances cannot be added in a high concentration to an oil so as to prepare an oil base corrosion inhibitor. To the extent that oil base composition can be prepared, such preparation takes a long time. Additionally, they are disadvantageous because of the toxicity originated from their organic amine moiety. Finally, both of the aforediscussed substances promote the corrosion of a system in which a nonferrous metal is in contact with and/or alloyed with a ferrous metal, which limits the utility of such substances.
It is also known, for example from U.S. Pat. No. 2,790,779, that some amino acids can be used as a corrosion inhibitor. The amino acids have, however, no volatility and therefore are not suitable for use as a vapor phase inhibitor.
One object of this invention is to provide vapor phase inhibitor compositions having high volatility and excellent anti-corrosive characteristics.
Another object of the invention is to provide essentially non-toxic vapor phase inhibitor compositions.
A further object of the invention is to provide vapor phase inhibitor compositions which are easy to handle and have excellent anti-corrosion characteristics and which are readily prepared and to provide a method of protecting metal by applying said vapor phase inhibitors to the metal.